Comments Structure

The next step for your app is to handle user comments. For this, you will need to set up a Comment model similar to what you did for Link.

You will run the following to generate the scaffolding for your Comment model.

rails g scaffold Comment body:text link_id:integer:index user:references

Running this command will generate a migration file db/migrate/<date_time>_create_comments.rb with the following content:

class CreateComments < ActiveRecord::Migration[5.2]
  def change
    create_table :comments do |t|
      t.text :body
      t.integer :link_id
      t.references :user, foreign_key: true

      t.timestamps
    end
    add_index :comments, :link_id
  end
end

user:references creates a new column in our database with _id appended to the end of the provided model name (user). In this file t.references creates a user_id column, a foreign key that points to the id of the user, and an index for it (recall indexesindex) .

This will allow you to use commands such as @comment.user to get the user who made a certain comment. All methods associated with user can be accessed through this once you create the associations.

the add_index line is similar to what you did for links and user_id. It will allow access to commands such as @comment.link as well as @link.comments after creating the appropriate associations.

Note: :references and :index both create an index in the table. :references was not used for links for the purpose of the upcoming challenge. You can visit the db/schema.rb file to get an understanding of the current database schema and of the indexes we have created.

Along with the migration file, the usual controller and view structure are also generated.